@davr And also note that the newest answer to that question correctly points out that some Intel storage controllers will pass TRIM to (non-RAID) SSDs, even if the controller is in RAID-mode.
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sblairMay 13 '10 at 17:10

If you get two, you can put them into Raid0. 0 means the amount of data that you will be able to recover after a failure. :P Or a raid1 which provides a good security against data loss. OR you can use one as a system drive and one for other stuff.. I don't really see a point in that. (However, if you tend to use Windows 7 (you should use that since its optimised for SSD), it'll eat your 30gb with a single bite. You should take the 60gb or two 30gb with RAID0 :))

I have 2 laptops with SSDs, one of them also has a spinning drive for all my junk. I'd go for 1 big drive in a laptop, please yourself in a desktop if you have space. That decision could depend more on cost and availability than on performance differences which may, or may not be noticeable.

2x SSDs won't be twice as fast as one and it won't be twice the difference from spinning rust. The 1st SSD is the order-of-magnitude difference, the 2nd is hte icing on the cake.

The point I would see is that you can have your OS/software on one device and data files, on the other device, both devices potentially transmitting/receiving AT THE SAME TIME. As those are slower ones than RAM, if everything is going through the same channel (CODE and DATA), you may experience delays that you could avoid if the bits were traveling on TWO different chips at the same time.

I guess this also depends on the amount of disk access you plan to have if you run Window$, chances are that you will have lots of accesses to OS/software. Also, this means that you can keep your data on a separate device that you can take to other computers, without requiring that you move your OS too.

if your are looking for performance gains by having your OS on a SSD, I would recommend that. However if you are going to be using windows rather than linux, you may run into an issue about drive size once you start installing programs after installing the OS. What I would do is buy a SSD for the OS drive and the other would be a regular HDD as large as possible for just plain storage - have the OS boot of the SSD for quicker booting times and the large storage space on the other drive.